Raichu (Japanese: ライチュウ Raichu) is an Electric-type Pokémon introduced in Generation I.
It evolves from Pikachu when exposed to a Thunder Stone. It is the final form of Pichu.
In Alola, Raichu has a dual-type Electric/Psychic regional form: Alolan Raichu. It evolves from Pikachu when exposed to a Thunder Stone. All Pikachu in Alola will evolve into this form regardless of their origin. It is the final form of Pichu in the Alola region.
Kantonian Raichu can Mega Evolve into two forms:
Mega Raichu X using the Raichunite X.
Mega Raichu Y using the Raichunite Y.
Both forms of Mega Raichu were introduced in the Mega Dimension DLC for Pokémon Legends: Z-A. Alolan Raichu cannot Mega Evolve.
So, this is how this works. You think of another representivie of a franchise, or a new one in general, and put them down here. Fire Emblem is not listed here for obvious reasons.